Electric switch



Dec. 24, 1935. R 5 B T 2,025,563

ELECTRIC SWITCH Filed 001;. 6, 1953 xix Invehtor: Ralph S: Bennett,

His A't'tovneg.

- Patented Dec. 24, 1935 PATENT OFFICE ELECTRIC swrron' Ralph S. Bennett, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Application October 6, 1933, Serial No. 692,469

8 Claims.

My invention relates to electric switches and more particularly to switches combined with fuses which are adapted to open upon operation of the fuse.

In the protection of overhead outdoor transmission lines it has become a common practice to combine a fuse with the line switch. For economy and safety, it is desirable to locate the switch and the fuse combined with it near the top of the pole adjacent the transmission line. The opening and closing of the switch may be accomplished by a long switch stick with a hook adapted to engage the switch handle. However, examination of the fuse to determine whether or not it has operated and replacement of the fusible element is hazardous due to the close proximity of the live switch contact and transmission line. Combined switches and fuses have been provided with an arrangement for auto- 50 matically opening the switch when the fuse operates. In this manner the operation of the fuse is clearly indicated without the necessity of a close examination. The automatic opening of the switch has the additional advantage of removing 25 the voltage stress from the fuse holder after the operation of the fuse. While the fuse is intact there is no voltage stress on the fuse holder. When the fuse has completed its operation before the switch begins to open no arc is drawn 30 between the switch and contact. On the other hand, if the switch does begin to open before the fuse has completed its operation, an arc may be drawn between the switch and contact which would do serious damage to the fuse holder and 36 may require its replacement.

An object of my invention is to provide an improved switch and combined fuse of rugged construction, easy to assemble and mount in position, and of relatively low cost of manufacture.

0 What I consider to be novel and my invention will be better understood by reference to the following specification and appended claims when considered in connection with the accompanying drawing, in which Fig. 1 is a perspective view of 45 the combined switch and fuse of my invention; Fig. 2 is an exploded view in perspective on an enlarged scale of a combined clamp and connector; Fig. 3 is an enlarged view in section of the combined clamp and connector in position;

50 and Fig. 4 is an enlarged sectional view of the fuse holder and contact cap.

Referring to the drawing, I0 indicates a cross arm secured to a pole, not shown, on which the transmission imes are carried. An insulator I I 55 is mounted on the cross arm by means of a strap I2 and a two-part clamp l3. Strap I2 consists of a flat strip of metal surrounding a central portion I4 of insulator II of reduced diameter. Strap I2 is held in close engagement with central portion It by means of a bolt I5. Strap I2 is 5 secured to one part of two-part clamp I3. The two parts of clamp I3 are secured in engagement with opposite sides of cross arm I0, which may vary in thickness, by means of bolts It. A metal rod H which may consist of copper forms a switch 10 contact I8 and extends around the upper end of insulator seating in an annular groove l9. The arrangement of the metal rod I! to form the switch contact I8 and supporting it in an annular groove l9 greatly simplifies the assembly 5 and reduces the cost of manufacture of the switch as compared with one supported on inserts ce-= mented in an opening in the insulator. The two free ends of rod I! are flared outwardly adjacent switch contact I8 and form a V between them to guide a movable switch contact to contact l8. To secure rod IT in firm engagement with insulator II and also to provide an electrical connection for switch contact I8 a combined clamp and connector 20 is provided. Referring to Fig. 2, it may be seen that combined clamp and connector 20 consists of two identical parts 2| and 22 which are provided with semi-circular transverse grooves 23 and 24 respectively in which the two parts of rod I! are adapted to be clamped. 'Ihesemi-circular shape of these grooves 23 and 24 provides surfaces which closely engage the rod I1 and clamp it tightly without any danger of severing the rod upon the tightening of the clamp. To guide rod into grooves 23- and 24, 36 longitudinal projections 25, 26, and 27 from part 2| and projections 28, 29, and 30 from part 22 are provided. Each of these projections have an inclined surface adjacent grooves 23 and 2G to gradually force the rod toward the center into the grooves 23 and 2.4 as parts 2% and 22 are drawn together. Projection 25 of part 2| passes between projections 29 and 30 of part 22, and projection 28 of part 22 passes between projections 26 and 27 of part 2| asthe two parts 6 are drawn together. To draw parts 2| and 22 together, a stud 3| is provided which passes through part 22 and threads into part- Zi. The head 32 of stud 3| engages the bottom surface of part 22 and draws part 2| tightly down against part 22 as it is threaded through the central opening 33 of part 2|. To provide for the electrical connection of a conductor 34 connected to one of the overhead transmission lines to rod it and switch contact I8, a longitudinal slot 35 is pro l3 is laid in the slot 35. To hold the bared end of conductor 34 in slot 35, a nut 36 is provided with a metal clip 31 which is adapted to slide in slot 35. Clip 31 is of substantially the width of slot 35 and is provided with a lower fiat contact surface 38 and two integral arcuate projections 39 and 48 which are adapted to pass through the opening of nut 36 and engage the opposite face to hold the clip 31 loosely in the nut 36. By this arrangement, a large contact .area-is provided for engagement with the bared end of conductor 34 and the conductor is clamped between two surfaces which do not have any tendency to sever the conductor 34. By the provision of combined clamp and connector 28 the switch contact I8 is held securely-in positon on insulator II and the electrical connection for the switch contact is provided with a minimum number of operations to mount the switch contact and make the electrical connection to rod l1. Secured to the lower end of insulator H is a rod 4| which seats in an annular groove 42. Rod 4| is held in position in groove 42 by means of a combined clamp and connector 43 which is identical to the combined clamp and connector 20. The'free ends of rod 4| are turned inwardly toward each other and pass into a cylindrical bushing 44 which provides a pivot for switch 45. ,A fuse holder 46- consisting of a tube of insulating material carries a fuse link 41 within its central bore extending from the lower open end of fuse holder 46. A cap 48 closes the upper end of fuse holder 46 and holds fuse link 41 in engagement with the top of fuse holder 46. As better indicated in Fig. 4, fuse link 41 has a contact button 49 which rests on the top of fuse holder tube 46. Contact cap 48 is threadeddirectly on the fuse holder tube 46. Between contact button ,49 and contact cap 48 a spiral spring 58 is located which serves to provide sufficient pressure to hold contact button 49 in engagement with the top of tube 46 despite ,a variation in the space provided in cap 48 to rotation of fuse holder 46 is prevented and opening of the switch retarded to permit the extinction of the are within fuse holder 46 before the beginning of the opening of switch 45. This arrangement is important because if switch 45 should open before the arc is extinguished within fuse holder 46, a secondary'arc may be drawn between the cap'48 and switch contact I8 which would be more dificult to extinguish than an are drawn within the fuse holder 46 and in addition may do serious damage to the fuse holder and,

support and require its subsequentreplacement. For the manual opening of switch 45 and its removal for replacement after operation of the fuse, operating handle 52 is provided and secured on fuse holder 46 adjacent to cap 48. To prevent radio interference by a static electric discharge between operating handle 52 and cap 48,

a copper wire spring 53 is provided engaging operating handle 52 and contacting with cap 48. Operating handle 52 is so formed as to permit the manual opening of the switch by the engage- 2,025,568 -vided m stud 31. The and end of conductor 34 ment of the usual hook provided on a switch stick and also for removal of the switch 45 by the same switch stick. The operating handle 52 and cap 48 with its conical projection are not my invention, but are the subject of another application Serial No. 692,414 filed concurrently herewith in the name of B. R. Hermann and assigned to the same assignee to which this application is assigned.

Fuse holder 46 is carried on rod 4| by a fuse 10 holder support 54 and toggle 55. Toggle 55 is pivotally connected to fuse holder support 54 by means of a pivot pin 56. Toggle 55 is pivotally supported on bushing 44. To prevent lateral movement of toggle'55, side plates 51 and 58 15 are provided and-secured to rod 4| on the adjacent ends of bushing 44. Fuse link 41 is connected to toggle 55 by means of a thumb screw 59. As long as the fuse is intact, toggle 55 is held in the position indicated in Fig. 1 with a projection 60 '20 in engagement with fuse holder support 54. Up-- on operation of the fuse, toggle 55 is released and rotates about bushing 44. Fuse holder 46 does not immediately follow the movement of toggle 55. Initially fuse holder 46 moves longitudinally 5 until projection 5| is freed from engagement with switch contact l8 and then it rotates about pivot pin 56 until fuse holder support 54 is in engagement with projection 68 'of toggle 55. The fuse holder tube 46 may then be removed from the 30 lower contact 4| and fuse link 41 renewed. Fuse holder 46 may then be replaced and the circuit completed in the usual manner by closing switch 45.

From the foregoing it will be seen that a com- 35 bined fuse and switch is provided .of rugged construction which is easy to assemble and mount in position and is of relatively low cost of manu- V facture.

What I claim as new and desire to secure by 0 Letters Patent of the United States, is:

1. An electric switch comprising an insulator,

a rod surrounding one end of said insulator and forming a contact surface near its free end, a sec- 0nd rod surrounding the other end of said insu- 1'5 lator, clamps to secure said rods to said insulator,

a fuse holder, means to support and pivot the fuse holder on said second-mentioned rod, a contact secured to said fuse holder and adapted to engage said first-mentioned rod, and means to so connect conductors to each of said rods.

2. An electric switch comprising an insulator, means to support said insulator, a stationary switch contact formed of a rod extending, about the end of said insulator, a clamp to secure said -55 contact to said insulator, a second switch contact formed of a rod surrounding the other end of said insulator, a clamp to secure said second contact to said insulator, a fuse holder, means to support and pivot said fuse holder on said '60 second-mentioned contact, a contact secured to said fuse holder and adapted to engage said firstmentioned contact, means to connect a conductor to said clamp securing the first-mentioned contact to the insulator, and means to connect a 65 conductor to said clamp securing the second mentioned contact to the insulator.

3. In an electric switch, an insulator, a stationary switch contact consisting of a rod passing around one end of said insulator and seated 70 in an annular groove, a two-part clamp engaging saidrod, a stud passing through said clamp to secure said clamp in close engagement with said rod, and a nut adapted to secure a conductor in a longitudinal slot in said stud. 15

4. A combined clamp and connector comprising a twopart clamp having interengaging parts and a transverse groove, a stud for securing said two-part clamp together with a rod seated in said transverse groove, said stud having a longitudinal slot, and a nut threaded on said stud and adapted to secure a conductor in the slot.

5. A combined clamp and connector comprising a part having a transverse groove and iongitudinal projections, a second part having a transverse groove adapted to register with the transverse groove in said first-mentioned part and having projections nesting with the projectionsin said first-mentioned part, a stud passing through said clamping portions for securing them together to clamp a rod in said transverse grooves and having a longitudinal slot, and a nut having a contact clip adapted to slide in the slot of said stud and engage a conductor to secure it in the slot when the nut is threaded on the end of the stud.

6. A combined connector and clamp adapted to secure a rod in an annular groove in an in-- sulator comprising a clamp having transverse grooves and projections with surfaces extending angularly from said grooves, a stud for securing said clamp on a rod which rod is guided to said grooves by said projections and adapted to be seated in said groovesby the tightening of the clamp, said stud having a longitudinal slot, a nut arranged to engage said stud and a contact clip secured to said nut and adapted to slide in the slot in said stud and secure a conductor in the slot when the nut is threaded on the end of the stud. 5

7. An electric switch comprising an insulator, a supporting strap passing around a reduced portion of said insulator, a metal rod secured in an annular groove in one end of said insulator, a second metal rod secured in an annular groove in the other end of said insulator, a fuse holder, a contact secured to said fuse holder and adapted to engage said first-mentioned rod, means to pivotally support said fuse holder on said second-mentioned rod, and means to connect a conductor to each of said rods.

8. An electric switch and support comprising an insulator, means to support said insulator, a metal rod secured in an annular groove in one end of said insulator, a contact surface formed between abutting ,ends of said rod, a second metal rod secured in an annular groove in the other end of said insulator, a fuse holder, 9. contact secured to said fuse holder and adapted to engage said first-mentioned rod, means to pivotally support said fuse holder on said sec end-mentioned rod, and means to connect a conductor to each of said rods.

RALPH S. BENNETT. 

